how to resolve check engine light issues in Toyota Highlander Fourth Generation (2020-present)?

Solution

1. Preparation

• Gather tools and parts needed for repairs.
• Ensure the vehicle is parked on a flat surface and the engine is cool.
• Disconnect the battery negative terminal to prevent electrical shorts.

2. Address Fault Codes

• Use the OBD-II scanner to retrieve and document the trouble codes.
• Research codes against manufacturer specifications to determine the cause.
• For common issues (e.g., P0420 for catalytic converter efficiency), replace the faulty component as needed.

3. Inspect and Replace Components

• Air Filter Replacement:
  • Remove the air intake cover.
  • Take out the old air filter and replace it with a new one.
• Spark Plug Replacement:
  • Remove ignition coils by disconnecting electrical connectors and unscrewing bolts.
  • Extract old spark plugs using a spark plug socket and install new ones, torquing to manufacturer specifications (typically around 13-15 lb-ft).

4. Clear Codes and Reconnect Battery

• Reconnect the battery negative terminal.
• Clear the trouble codes using the OBD-II scanner.

5. Test Drive

• Drive the vehicle for at least 20 minutes to allow the engine to reach operating temperature.
• Monitor the dashboard for the check engine light to see if it re-illuminates.